@Necropolis00 The powers are fairly much equal, and on a different day I might have made a different choice. If you're omnipotent over magic, you can make your Self magic and be omnipotent over yourself. And if you're omnipotent over your Self, you can grant yourself omnipotent magicks. I guess.
Maybe I thought Aracanoscience would be useful for understanding how to properly make external changes to the multiverse and not fouling up, because you have the proper spells? The proper spells to utilize multiversal-level Cosmic Knowledge, Reality Selection, and Temporal Rewind? We wouldn't want to accidentally destroy reality with gobs of raw power, and having some cosmic grimoires in your brain on all that might be useful.
The same effects can probably be reached by Autopotence through another route, though. You could make your Self a living Cosmic Library that knows all, and then go from there, I guess.